Flow restrictor



C. F. ALSING FLOW RESTRICTOR Filed Aug. 31, 1955 WITNESSES:

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INVENTOR CARL. E ALSLNG.

ATTORN Patented Oct. 25, 1938 UNITED STATES FLOW RE STRICTOR Carl F. Alsing, Springfield, Mass, assignor to Westinghouse Electric & Manufacturing Conn pany, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 31, 1936, Serial No. 98,754

3 Claims.

My invention relates to aflow restrictor for restricting the flow of fluid from a high to a low pressure region, and particularly to a flow restrictor for restricting and lowering the presi sure of liquid refrigerant passing from the condenser to the evaporator of a refrigerating system.

It is an object of my invention to provide an improved flow restrictor of the capillary passage type in which clogging of the passage by lint and dirt is practically eliminated.

It is another object of my invention to provide an improved flow restrictor of the capillary tube type for use in a refrigerating system in which refrigerant and lubricant are in contact with the windings of the motor driving the compressor.

These and other objects are effected by my invention-as will be apparent from the following description and claims taken in connection with the accompanying drawing and forming apart of this application, in which:

Fig. i is a diagrammatic view of 'a compressor refrigerating system embodying my invention; and,

Fig. 2 is an enlarged view of the inlet end of the flow restrictor shown in Fig. 1 as a capillary tube.

Referring to the drawing for a detailed description of my invention, numeral l l designates a sealed casing containing a motor l2 and a refrigerant compressor i3. Refrigerant is drawn from the interior of the casing H through a compressor inlet i l and compressed refrigerant is forced through an outlet conduit IE to a condenser lt wherein it is condensed by the air driven over the condenser by a fan IT. Liquid refrigerant is conveyed from the condenser l6 through a conduit i8 to a flow restricting and pressure reducing device generally indicated at l9 (Fig. 1). Refrigerant is admitted through the flow restricting device M to an evaporator 2|, wherein liquid refrigerant at low pressure vaporizes and absorbs heat. Refrigerant vapor is withdrawn from the evaporator 2| through a conduit 22 by the action of the compressor l3 and enters the interior of the sealed casing H, where it comesin contact with windings 23 of the motor l2. The motor windings are usually insulated with cloth or paper and shreds of the insulation may be present in the refrigerant.

The flow restricting device l9 preferably comprises a helically coiled tube 24 of considerable length and having a passage 25 therein of relatively small bore so as to restrict the flow of liquid from the condenser to the evaporator 2!.

iii

Such devices are referred to by some in the refrigerator art as capillary tubes. One end 26 of the tube 24 extends into the evaporator 2|, and the inlet end 21 of the tube extends into a fitting 28 having a chamber 29 into which liquid 5 refrigerant from the condenser i6 is conveyed through the conduit Hi.

In refrigerating systems employing capillary tube type flow restricting devices, the inlet end of the small passageway in the tube may clog because small shreds of lint from the insulation on the motor, pieces of dirt and the like catch on the sharp edges of the tube, crosswise of the opening of the passage 25. After a few such particles adhere to the inlet of the tube, other par- 35 ticles add rapidly to those already caught and eventually bridge and clog the passage, necessitating opening the system to clean the tube, which is obviously very expensive and troublesome.

In order to obviate these difllculties, I have rounded the inlet edge of the tube 245, as shown at 35. I have, furthermore, tapered the outer surface of the tube at the inlet end as shown at 32. By so forming the capillary tube 2t, shreds of lint, dirt and the like, when they contact the rounded edge and tapered sides 32, slide ed the edge and either pass through the passage 25 lengthwise, as shown at 33, or pass to the outside of the tube 2d along the tapered sides 32. Furthermore, by rounding the edge of the tube 24, its flow characteristics are improved because turbulence at the inlet thereof is reduced.

From the foregoing it will be apparent that I have provided an improved flow-restricting device which will not clog up with lint and dirt, and which is designed for use with a hermetically sealed motor-compressor unit wherein the refrigerant is in contact with the insulated windings of the motor.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without de parting from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is: v

1. In a refrigerating system, the combination of a condenser and an evaporator in which refrigerant is successively condensed and evaporated, said condenser forming a part of the high pressure region of the system, and a device for restricting the flow of refrigerant between the condenser and the evaporator, said device comprising a tube having a restricted flow passage therein, the inner edge of the tube at the inlet end having inwardly converging walls, forming which system includes an evaporator and a condenser in which refrigerant is successively evaporated and condensed, said condenser forming a portion of a high pressure region of the refrigerating system, said capillary tube having a relatively restricted bore of uniform diameter for controlling the flow of liquid refrigerant from the condenser to the evaporator, the walls of the bore being curved outwardly adjacent the extremity of the tube, said curved walls meeting at a point adjacent the entrance of the tube,

whereby a smooth surface is provided at said inlet end, said high pressure region of the refrigerating system having a portion of larger cross sectional area than the area defined by the outer circumference of said tube, and said inlet end of the tube extending into the portion of the relatively larger flow area.

3. In a refrigerating system, the combination of an evaporator and a condenser in which re-' frigerant is successively evaporated and con-- densed, said condenser formin a portion of the high pressure region of the refrigerating system, a motor and a compressor for circulating refrigerant to the evaporator and condenser, a sealed casing for enclosing the motor and containing some of said refrigerant in contact with both the motor and compressor, and means including a capillary tube having a relatively restricted bore of uniform diameter for controlling the flow of liquid refrigerant from the condenser to the evaporator, the walls of the bore being curved outwardly adjacent the extremity of the tube, and the outer walls of the tube being curved inwardly adjacent the extremity of the tube, said curved walls meeting at a point adjacent the entrance of the tube, whereby a smooth surface is provided at said inlet end, said high pressure region of the refrigerating system having a portion of larger cross sectional area than the area defined by the outer circumference of said tube, and said inlet end of the tube extending into the portion of the relatively larger flow area.

CARL F. AISING.

and compressor 2 

